docs: def process_document(self, doc, std):
          """callback to insert index"""
          if doc.url not in self.blacklist:
              print("Indexing '%s' %s..." % (doc.url, std))
              name = self.extract_name(doc.text)
              self.results.add((name, doc.url, std))
          else:
              print("Skipping blacklisted page '%s' ..." % doc.url)
              return None